1. Field of the Invention
The present invention relates to a GPS receiving antenna attached to the outside of a moving object such as a ship or an automobile to receive a radio wave generated from a GPS (Global Positioning System) satellite.
2. Description of the Prior Art
The configuration of a conventional GPS receiving antenna will now be described with reference to FIGS. 4 and 5. A box-shaped upper case 21, which is formed by molding a synthetic resin, comprises an upper wall 21a, side walls 21b extending from four sides of the upper wall 21a, a receptacle portion 21c surrounded by the upper wall 21a and side walls 21b and whose underside is open, and stepped portions 21d formed as recesses in and along the side walls 21b. 
A box-shaped lower case 22, which is formed by molding a synthetic resin, comprises a bottom wall 22a, side walls 22b extending from four sides of the bottom wall 22a, a receptacle portion 22c surrounded by the bottom wall 22a and side walls 22b and whose upper side is open, stepped portions 22d formed as projections in and along the side walls 22b, and a pair of recess portions 22e each formed in the shape of a rectangular parallelepiped in the underside of the bottom wall 22a. 
The upper and lower cases 21, 22 are combined together so that the receptacle portions 21c and 22c are opposed to each other and are mounted together by a suitable means.
As a result, a single receptacle portion is formed by the receptacle portions 21c and 22c and the stepped portions 21d and 22d are fitted together, with a packing being mounted in each of the thus-fitted portion to seal the interiors of the receptacle portions 21c and 22c. Thus, there is provided a waterproof configuration against the entry of water, etc.
An antenna body 24 is made up of: an earth plate 25; an antenna element 26 for receiving a radio wave from a GPS satellite, the antenna element 26 being provided on the surface side of the earth plate 25; a dielectric substrate 27 provided on the back side of the earth plate 25, with electric components (not shown) such as resistors, capacitors and IC parts being mounted on the substrate 27; and a shielding case 28 for shielding the dielectric substrate 27 electrically.
The antenna body 24 thus constructed is accommodated within the sealed receptacle portions 21c and 22c in such a manner that the shielding case 28 lies on the bottom wall 22a side of the lower case 22.
A waterproofing sleeve 30 is fitted on an outer surface of a coaxial cable 29 and the coaxial cable 29 is mounted in a state such that the sleeve 30 is sandwiched between the upper and lower cases 21, 22. The coaxial cable 29 is connected to the dielectric substrate 27 and is drawn out to the exterior.
A pair of magnets 31, each in the shape of a rectangular parallelepiped, are received respectively within the recess portions 22e of the lower case 22 and are attached to the lower case 22 with an adhesive 32 applied into the recess portions 22e. 
By utilizing the magnetism of the magnets 31, the GPS receiving antenna thus constructed is attached by attraction to the outside of a moving object such as a ship or an automobile (the roof of an automobile, for example).
In the conventional GPS receiving antenna, since the adhesive 32 for mounting the magnets 31 is applied into the recess portions 22e of the lower case 22, the adhesive 32 applied to upper surfaces of the recess portions 22e is forced out to the exterior of the recess portions 22e by being pushed with the magnets 31, thus giving rise to the problem that not only the commercial value is impaired but also surface-attraction of the magnets 31 is obstructed by the thus-protruded adhesive 32, resulting in the mounting of the GPS receiving antenna becoming unstable.
Moreover, since the antenna body 24 is merely accommodated within the receptacle portions 21c and 22c, the mounting thereof is unstable and there occurs wobbling.
Accordingly, it is an object of the present invention to provide a GPS receiving antenna free of adhesive protrusion, capable of ensuring magnet attraction, and with an antenna body mounted firmly.
According to a first aspect of the present invention, there is provided a GPS receiving antenna comprising upper and lower cases; an antenna body received in a receptacle portion formed by the upper and lower cases; and a magnet received in a recess portion formed in a lower surface of a bottom wall of the lower case and bonded to the lower case with an adhesive, wherein a hole for communication between the recess portion and the receptacle portion is formed in the bottom wall in which the recess portion is formed, and the adhesive is applied into the hole to bond the antenna body and the magnet with each other.
According to a second aspect of the present invention there is provided, in combination with the above first aspect, a GPS receiving antenna wherein a depression is formed in the lower surface of the bottom wall opposed to the magnet so that the adhesive is present in the depression.